Javascript code to merge first name, last name and Address in a pdf form

- This was discussed many (many) times in the past. Basically, you can do it like this (as the custom Calculation script of the merged text field):

event.value = this.getField("first_name").valueAsString + " " + this.getField("last_name").valueAsString + " " + this.getField("address_name").valueAsString;

- This is not possible. Each signature field has to be unique, and you can't copy the value from one to another.

Also, there's no need to do that, as a (digital) signature applies to the entire file as a whole, not to a specific page in it.